topicmap: massive rework Massively rework the way we build and use topicmap. This bring massive performance benefit. Topic map use to be a fully independant thing that we would switch on and off globaly. The caching on disk was broken so the performance were atrocious. Intead, now the topic are inherited from the 'immutable' map. We gave up on storing them on disk for now since the mutable set is usually small enough. The activation is done by hacking new "filter" on the repository and detection when they are one. This is hacky but core is hard to wrap here. Overall this whole wrapping is really scary and we should massage core API to help it.